A) \[1440\text{ }Hz\]
B) \[240\text{ }Hz\]
C) \[1200\text{ }Hz\]
D) \[960\text{ }Hz\]
Correct Answer: C
Solution :
From Doppler's effect, the perceived frequency \[(f')\] is given by \[f'=\left( \frac{v-{{v}_{o}}}{v-{{v}_{s}}} \right)f\] where \[{{v}_{o}}\] is velocity of observer, \[{{v}_{s}},\] of source, v of sound and / the original frequency. Given, \[{{v}_{o}}=0\] (stationary), \[v=300\text{ }m/s\] \[{{v}_{s}}=200m/s,\,\,\,\,\,\,f=400Hz.\] \[\therefore \] \[f'=\frac{300\times 400}{300-200}=\frac{300\times 400}{100}\] \[\Rightarrow \] \[f'=1200Hz\]You need to login to perform this action.
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